Heat exchangers often define a wall separating two fluids with different levels of energy, as demonstrated by different temperatures for example. Thermal energy, or heat, is transferred from the fluid at higher temperature, through the wall, to fluid at lower temperature.
Stirling cooling systems can incorporate heat exchangers. A Stirling cooling system, or Stirling heat transfer system, applies compression and expansion to a compressible working fluid to transfer heat. Usually the working fluid is helium or hydrogen. The Stirling system includes an elongate tube or conduit, a pair of pistons moving in the tube, and regenerating member disposed between the pistons. The pistons are moved together and relative to one another to compress and expand the fluid. As a result of the coordinated movement of the pistons, one end of the tube rejects heat and the opposite end of the tube absorbs heat. Heat exchangers can be disposed at both ends to enhance the transfer of thermal energy.